The present invention relates to a combustion chamber. More specifically, the present invention relates to a system and method for achieving fast exhaust gas recirculation in a combustion chamber.
Conventional spark-ignited internal combustion engines employ a combustion chamber into which fuel is directed and ignited. In order to reduce the fuel consumption of the engine, exhaust gas recirculation may be used. Exhaust gas recirculation may also be used in an engine to reduce nitrous oxide (NOx) and hydrocarbon emissions.
One example of an exhaust gas recirculation system, such as that shown and described in U.S. Pat. No. 5,894,826, include an internal combustion engine defining a combustion chamber for the direct injection of fuel through a centrally located fuel injector. The combustion chamber has a first inlet passage and port for directing hot exhaust gases of a recirculation medium to a central region of the combustion chamber. The combustion chamber also has a second inlet passage and port for directing air tangentially into the combustion chamber to cause a circular flow about the chamber""s periphery and about the exhaust rich central region. The injector sprays fuel through the hot exhaust gas medium in the central region which results in a pre-heating of the fuel, thereby reducing hydrocarbon emissions prior to ignition by a spark plug located adjacent the periphery of the combustion chamber.
Several problems exist with conventional exhaust gas recirculation systems. For instance, conventional exhaust gas recirculation systems typically use exhaust gas from the motor vehicle""s exhaust manifold. However, the exhaust manifold is usually located at a significant distance, e.g., about 15 inches, from the combustion chambers. Because of this large distance, recirculated exhaust gas is typically not available, or else too much is available, for use in the combustion chamber for a fairly significant amount of time. In addition, it is often difficult to evenly distribute the exhaust gas between the various combustion chambers that are operating in the engine. Still further, since exhaust gas exhibits transient behavior, the amount of exhaust gas that can be used is often limited.
Thus, there is a need to provide an exhaust gas recirculation system and method that achieves fast exhaust gas recirculation in a combustion chamber.
It is therefore an object of the present invention to provide an exhaust gas recirculation system and method that increases the speed with which exhaust gas recirculation may be employed in a combustion chamber.
It is also an object of the present invention to provide an exhaust gas recirculation system and method that improves the fuel economy of an engine.
It is another object of the present invention to provide a system and method that provides more equal distribution of recirculated exhaust gas to combustion chambers.
The above and other beneficial objects of the present invention are achieved by providing a system and method as described herein. The present invention, according to one example embodiment thereof, relates to an exhaust gas recirculation system that includes a combustion chamber having at least one intake port in communication with the combustion chamber. The intake port has a corresponding intake valve for controlling a flow through the intake port into the combustion chamber. The combustion chamber also has at least one exhaust port in communication with the combustion chamber. The exhaust port has a corresponding exhaust valve for controlling a flow through the exhaust port from the combustion chamber.
In addition, the combustion chamber has at least one exhaust gas recirculation port in communication with the combustion chamber. The exhaust gas recirculation port may also be in communication with the exhaust port external to the combustion chamber. The exhaust gas recirculation port may have a corresponding exhaust gas recirculation valve for controlling a flow through the exhaust gas recirculation port into the combustion chamber. The exhaust gas recirculation valve is separately actuatable from the intake valve and the exhaust valve. The exhaust gas recirculation valve may be actuatable according to at least one engine operating condition, such as the engine load, determinable from an engine operating condition sensor. In addition, the exhaust gas recirculation system may include a controller that is configured to control the operation of the exhaust gas recirculation valve.